merge-base.c

   1 #include <stdlib.h>
   2 #include "cache.h"
   3 #include "commit.h"
   4
   5 static struct commit *process_list(struct commit_list **list_p, int this_mark,
   6                                    int other_mark)
   7 {
   8         struct commit_list *parent, *temp;
   9         struct commit_list *posn = *list_p;
  10         *list_p = NULL;
  11         while (posn) {
  12                 parse_commit(posn->item);
  13                 if (posn->item->object.flags & this_mark) {
  14                         /*
  15                           printf("%d already seen %s %x\n",
  16                           this_mark
  17                           sha1_to_hex(posn->parent->sha1),
  18                           posn->parent->flags);
  19                         */
  20                         /* do nothing; this indicates that this side
  21                          * split and reformed, and we only need to
  22                          * mark it once.
  23                          */
  24                 } else if (posn->item->object.flags & other_mark) {
  25                         return posn->item;
  26                 } else {
  27                         /*
  28                           printf("%d based on %s\n",
  29                           this_mark,
  30                           sha1_to_hex(posn->parent->sha1));
  31                         */
  32                         posn->item->object.flags |= this_mark;
  33
  34                         parent = posn->item->parents;
  35                         while (parent) {
  36                                 temp = malloc(sizeof(struct commit_list));
  37                                 temp->next = *list_p;
  38                                 temp->item = parent->item;
  39                                 *list_p = temp;
  40                                 parent = parent->next;
  41                         }
  42                 }
  43                 posn = posn->next;
  44         }
  45         return NULL;
  46 }
  47
  48 struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
  49 {
  50         struct commit_list *rev1list = malloc(sizeof(struct commit_list));
  51         struct commit_list *rev2list = malloc(sizeof(struct commit_list));
  52
  53         rev1list->item = rev1;
  54         rev1list->next = NULL;
  55
  56         rev2list->item = rev2;
  57         rev2list->next = NULL;
  58
  59         while (rev1list || rev2list) {
  60                 struct commit *ret;
  61                 ret = process_list(&rev1list, 0x1, 0x2);
  62                 if (ret) {
  63                         /* XXXX free lists */
  64                         return ret;
  65                 }
  66                 ret = process_list(&rev2list, 0x2, 0x1);
  67                 if (ret) {
  68                         /* XXXX free lists */
  69                         return ret;
  70                 }
  71         }
  72         return NULL;
  73 }
  74
  75 int main(int argc, char **argv)
  76 {
  77         struct commit *rev1, *rev2, *ret;
  78         unsigned char rev1key[20], rev2key[20];
  79
  80         if (argc != 3 ||
  81             get_sha1_hex(argv[1], rev1key) ||
  82             get_sha1_hex(argv[2], rev2key)) {
  83                 usage("merge-base <commit-id> <commit-id>");
  84         }
  85         rev1 = lookup_commit(rev1key);
  86         rev2 = lookup_commit(rev2key);
  87         ret = common_ancestor(rev1, rev2);
  88         if (!ret)
  89                 return 1;
  90         printf("%s\n", sha1_to_hex(ret->object.sha1));
  91         return 0;
  92 }